The world's largest solar bag-you've never seen a solar bag like this one! Our 50-foot-long, 3-foot diameter, black plastic solar bag holds over 350 cubic feet of air. Simply fill with air, tie off the ends, and let the solar energy of the sun heat the air inside the bag. In less than ten minutes, the bag will rise into the sky. The solar bag rises so fast it must be tethered to hold it down. In less than one class period, density and buoyancy are taught in a very dramatic way. Detailed instructions included.